1. Field of the Invention
This invention is directed to an improved petroleum residua upgrading process comprising the hydrotreatment of resids in the presence of metal containing amorphous magnesia-alumina-aluminum phosphate catalyst. The invention also relates to the catalyst used in the process.
2. Background Art
It is well known that many if not most petroleum based stocks contain contaminants as for example, sulfur, nitrogen and metals. It is desirable, particularly if these feedstocks are to be further processed, that the contaminants be removed. This is an operation usually requiring use of a catalyst.
It has been conventional in the art to effect contaminant removal, such as sulfur removal from hydrocarbon stocks, by subjecting them to treatment with hydrogen at elevated temperature and pressure while in contact with a catalyst containing hydrogenating components. Typically the hydrogenating components of such known catalysts are Group VIB or VIII metals, or other oxides or sulfides. These hydrogenating components may be supported on a variety of well known carriers, for example, alumina, kiselguhr, zeolitic molecular sieves and other materials having high surface areas: U.S. Pat. No. 4,080,296. U.S. Pat. No. 3,546,103 teaches hydrodesulfurization with a catalyst of cobalt and molybdenum on an alumina base. U.S. Pat. No. 3,755,146 describes a process for preparing lube oils characterized by low pour points which utilizes a catalyst mixture comprising hydrogenation components, a conventional cracking catalyst which can be either crystalline or amorphous and a crystalline aluminosilicate of the ZSM-5 type.
Hydrotreating of distillates may be defined simply as removal of sulfur, nitrogen and metal compounds by selective hydrogenation. The hydrotreating catalysts used commercially are cobalt plus molybdenum or nickel plus molybdenum used in the sulfided forms and impregnated on an alumina base. The hydrotreating operating conditions are such that appreciable hydrogenation of aromatics does not occur; these are about 1000 to 2000 psi hydrogen and about 700.degree. F. The theoretical hydrogen consumption should be that required to hydrogenate the sulfur, nitrogen and metal-containing molecules and produce hydrogen sulfide and ammonia. However, the desulfurization reactions are invariably accompanied by small amounts of hydrogenation and hydrocracking, the extent of which depends on the nature of the feedstock and the severity of desulfurization.
This invention relates to a petroleum residua upgrading process. It comprises hydrotreatment of atmospheric or vacuum resids in the presence of a catalyst. The catalyst is a metal-containing amorphous magnesia-alumina-aluminum phosphate (MAAP).
The synthesis and use of similar compounds as supports for cracking and hydrocracking catalysts have been described in U.S. Pat. Nos. 4,179,358; 4,210,560; and 4,376,067, which are hereby incorporated by reference. More particularly, amorphous catalytic supports consisting of magnesia-alumina-aluminum phosphate are disclosed in U.S. Pat. No. 4,210,560, which is hereby incorporated by reference. U.S. Pat. No. 4,376,067 is a related patent disclosing substitution of a Group IIB component consisting of zinc or cadmium for magnesium. These supports are prepared by mixing together aqueous solutions of magnesium nitrate, aluminum nitrate and phosphoric acid and precipitating with ammonium hydroxide at a pH of about 9.0.
U.S. Pat. Nos. 4,382,877 and 4,382,878 also describe the use of MAAP-based catalysts. These patents are hereby incorporated by reference.
The above patents relate to the use of MAAP-based catalysts for hydrotreating. They describe advantages for lowering nitrogen and sulfur content of hydrogen feedstocks, but did not affect metals removal. Regarding certain of the FCC-related patents, there is description of advantages of MAAP FCC catalyst with regard to metals tolerance.
The importance of pore size distribution in catalyst or catalyst carrier is taught in U.S. Pat. No. 4,328,127.
However, neither the prior art mentioned above nor any known to applicants relate to the use of an organically-modified MAAP, exclusive of a cracking component, for demetallization and desulfurization of resids. It is only applicants who have discovered hydrodemetallization advantages obtained through use of organically-modified MAAPs. Moreover, the pore size distribution of applicants' material is distinctively different than previous MAAPs. This being achieved through applicants' discovery relating to the use of organic precipitating agents in the preparation of magnesia-alumina-aluminum phosphate supports. Applicants have further discovered that the pore size distribution of an amorphous material can be tailored by using organic compounds. Applicants have further discovered that by varying the type of and amount of organic present in the MAAP catalyst that the pore size distribution can be modified and certain pore diameter populations can be enhanced. All this is neither disclosed nor suggested in the art. With this in mind, applicants will proceed with a summary of the novel features of the present invention.